Hi Pipeline,
Yes it does that with me as well. It shows that the file type being saved is SEQ but only the filename appears in the upper box with no extension. I know this doesn't mean that it will not actually be saved as an SEQ. In my case if I follow through with this action then the file is saved with no extension at all and so is not listed in the available file types when I come to try and open it again. Also, if I do this the first time after loading an SGU file then I am also asked for Melody and Soloist track details and I don't really know what it's asking me so I just OK it.